This invention relates to the formation of a deposit of carbon within the lumen of a substrate and improved catheters, grafts, and the like, employing such internally coated carbon.
More specifically, but without restriction to the particular use which is shown and described, this invention relates to a device and method for coating the lumen of a substrate, such as used in grafts, catheters, and the like, used in living bodies.
It has been established that carbon coated surfaces used in vascular grafts or catheters, or other substrates for other uses are rendered less thrombogenic and more biocompatible by being coated with pure carbon. In the past, the outer surfaces of catheters and grafts could be more readily coated by RF sputtering techniques. The processes by which substrates are coated with carbon externally are not satisfactory to deposit carbon in the lumen of the device. In certain applications of catheters or grafts, it is much more critical that the lumen be rendered non-thrombogenic than is the exterior surface. In fact, if the substrate is a vascular graft, it is apparent that there is little reason to coat the exterior with carbon, but is highly advantageous that the lumen surface be so coated to prevent clogging by clotted blood.
In the employment of vessels leading to and from the heart, mechanical means to prevent or correct clogging have been, in many instances, ineffective. Often cracks or other discontinuites may occur through such techniques resulting in subsequent clogging. By carbon coating the lumen of a graft or similar vessel, the necessity of mechanically operating on implanted grafts, catheters, and the like to prevent such problems would be largely alleviated.
The coating of the lumen with carbon has presented difficult problems in the past. The use of heat to deposit the carbon can adversely affect the material of the catheter, graft, and the like. In addition, no prior art technique has been able to attain a good bond between the carbon and the internal surface which is also capable of maintaining a carbon interface between the catheter and the substance in the lumen, such as blood, and the like. Finally, it is extremely difficult to provide a uniform thin coating of the carbon within the lumen.